Actually i understand what is backtracking, which is the state when the engine applies a greedy quantifier, which result in other atom failure so the engine starts to backtrack to the previous state to give up matchings gradually in the sake of matching remaining atoms.but i got unexpected behavior when used this pattern "[^"]*" on this "abcv, which i wrote it to check what happens on failure. and i expected the engine to take these step:the engine matches "then the greedily quantified negated character set will match abcvthe engine fails to match the last "so it should backtrack to the [^"]* to give up characters one by one trying to match the remaining atom.but when i test this on regex101, the engine doesn't backtrack, but it starts over from another position each time it fails. so what am i missing here?Is this what exactly been expected? if so, would any one explain why?UpdateI need to mention that ".*" backtracks and if you check the engine steps you will find that it starts giving characters one by one but the one with issue doesn't. why this difference while both .* and [^"]* are greedy quantifiers which matched the same text, but one had to back track, the other hadn't.